Priority is claimed on Japanese Patent Application No. 2007-051299, filed Mar. 1, 2007, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a seatbelt apparatus.
2. Description of Related Art
A conventional seatbelt apparatus is known in which a motor as a driving source for winding a belt is provided, and the belt is wound around a belt reel upon connecting the motor to the belt reel at the time a passenger needs to be restricted. In order to appropriately wind the belt, the seatbelt apparatus includes a drawing and winding amount measuring unit. A rotation of the belt reel is controlled based on the measured result obtained by the drawing and winding amount measuring unit (e.g., see Japanese Unexamined Patent Application, First Publication No. 2005-297781).
The drawing and winding amount measuring unit includes a disk-like rotation member in which a portion for passing magnetic flux and a portion for shielding magnetic flux are alternatively arranged in the circumferential direction so as to be positioned on the same axis of the belt reel, and two hall elements which are arranged with the rotation member interposed therebetween so that an attachment angle is different from that of a magnet. Accordingly, the drawing and winding amount measuring unit can accurately measure a drawing and winding amount of the belt based on the output from the hall elements.
However, in the above-described seatbelt apparatus, since the belt may be drawn or wound irrespective of whether an ignition of a vehicle is in an ON state or an OFF state, it is necessary to detect a current position of the belt by operating the drawing and winding amount measuring unit even when the ignition is in an OFF state. Meanwhile, consumption current of the hall elements may be in a high state or a low state depending on the detection position, and thus when the hall elements are stopped in the state where consumption current is in a high state, dark current as consumption current is maintained in a high state when the ignition is in an OFF state, thereby increasing a load on a battery.
Therefore, an object of the present invention is to provide a seatbelt apparatus that is designed to reduce a load of a battery by restricting dark current.